The domestic cat serves as a valuable animal model because of its elaborate background in leukemia-sarcoma and the natural history of cancer. To ensure availability of animals with specific genetic backgrounds, considerable efforts are being made to define the reproductive-endocrine relationships, thereby maximizing reproductive potential within our breeding colonies. A series of comprehensive investigations have been conducted to (1) establish ovarian-endocrine relationships in the female cat during estrus, pregnancy, parturition and the postpartum interval; (2) study the influence of exogenous gonadotropins on ovarian function; and (3) determine testes-endocrine correlates in male cats. Overall, such information is being utilized to improve reproductive efficiency and breeding management within the feline colonies. Furthermore, techniques and findings from these studies have been applied and extended to reproductive, genetic and evolutionary analyses of both domestic and nondomestic Felidae, some of which are endangered.